Mechanisms for the effects of fish oil lipid emulsions in the management of parenteral nutrition-associated liver disease

Parenteral nutrition (PN) can be life saving for infants unable to adequately absorb enteral nutrients due to intestinal failure from inadequate bowel length or function. However, long-term PN carries significant morbidity and mortality, with 30 to 60% of patients developing progressive liver dysfunction. The etiology of PN-associated liver disease (PNALD) is poorly understood, however the involvement of lipid emulsions in its pathogenesis has been clearly established, with new emphasis emerging on the role of omega-6 polyunsaturated fatty acids and omega-3 polyunsaturated fatty acids. Recent studies evaluating the use of parenteral fish oil lipid emulsions instead of soybean oil lipid emulsions have demonstrated marked improvements in cholestasis, morbidity, and mortality in patients with PNALD treated with fish oil. This review provides an overview of the role of lipid emulsions in the pathogenesis of PNALD and the proposed mechanisms by which parenteral fish oil lipid emulsions may be exerting their beneficial effects.